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drm/i915/dp: Cache max common lane count

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Cache the maximum common lane count together with the common link
rates.

This is safe because the cached value is updated:
- during driver probe, before the connector is registered and can be
  used for mode validation or modesetting
- during resume, before output HW state readout can query it
- during connector detection, right after updating the sink/link
  capabilities

Caching the value allows detecting max common lane count changes in
a follow-up change and keeps the tracking of max common lane count
aligned with that of common rates.

Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20260522160514.2628249-4-imre.deak@intel.com
This commit is contained in:
Imre Deak 2026-05-22 19:05:13 +03:00
parent 0759e16078
commit cc18eac531
2 changed files with 9 additions and 2 deletions
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1
drivers/gpu/drm/i915/display/intel_display_types.h
View File

@ -1823,6 +1823,7 @@ struct intel_dp {
/* intersection of source and sink rates */
int num_common_rates;
int common_rates[DP_MAX_SUPPORTED_RATES];
int max_common_lane_count;
struct {
/* TODO: move the rest of link specific fields to here */
bool active;

10
drivers/gpu/drm/i915/display/intel_dp.c
View File

@ -363,7 +363,7 @@ int intel_dp_max_source_lane_count(struct intel_digital_port *dig_port)
}
/* Theoretical max between source and sink */
int intel_dp_max_common_lane_count(struct intel_dp *intel_dp)
static void intel_dp_set_max_common_lane_count(struct intel_dp *intel_dp)
{
struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
int source_max = intel_dp_max_source_lane_count(dig_port);
@ -374,7 +374,12 @@ int intel_dp_max_common_lane_count(struct intel_dp *intel_dp)
if (lttpr_max)
sink_max = min(sink_max, lttpr_max);
return min3(source_max, sink_max, lane_max);
intel_dp->max_common_lane_count = min3(source_max, sink_max, lane_max);
}
int intel_dp_max_common_lane_count(struct intel_dp *intel_dp)
{
return intel_dp->max_common_lane_count;
}
static int forced_lane_count(struct intel_dp *intel_dp)
@ -810,6 +815,7 @@ static void intel_dp_set_common_rates(struct intel_dp *intel_dp)
static void intel_dp_set_common_link_params(struct intel_dp *intel_dp)
{
intel_dp_set_common_rates(intel_dp);
intel_dp_set_max_common_lane_count(intel_dp);
intel_dp_link_config_init(intel_dp);
}